<template>
     <section class="msite">
        <!--首页头部-->
        <!-- slot通信传值：父组件向子组件传递标签数据 -->
        <HeaderTop :title="address.name">
          <router-link class="header_search" slot="left" to="/search">
            <i class="iconfont icon-sousuo"></i>
          </router-link>
          <router-link class="header_login" slot="right" :to="userInfo._id ? '/userinfo' : '/login'">
          <span class="header_login_text" v-if="userInfo._id"><i class="iconfont icon-geren"></i></span>
            <span class="header_login_text" v-else>登录|注册</span>
            
          </router-link>
        </HeaderTop>
        <!--首页导航-->
        <nav class="msite_nav">
          <div class="swiper-container" v-if="categorys.length">
            <div class="swiper-wrapper">
              <div class="swiper-slide" v-for="(categorys, index) in categorysArr" :key="index">
                <a href="javascript:" class="link_to_food" v-for="(category, index) in categorys" :key="index">
                  <div class="food_container">
                    <img :src="baseImageUrl + category.image_url ">
                  </div>
                  <span>{{category.title}}</span>
                </a>
              </div>
            </div>
            <!-- Add Pagination -->
            <div class="swiper-pagination"></div>
          </div>
          <img src="./images/msite_back.svg" alt="back" v-else>
        </nav>
        <!--首页附近商家-->
        <div class="msite_shop_list">
          <div class="shop_header">
            <i class="iconfont icon-xuanxiang"></i>
            <span class="shop_header_title">附近商家</span>
          </div>
          <ShopList></ShopList>
        </div>
      </section>
</template>

<script>
import Swiper from 'swiper'
import 'swiper/dist/css/swiper.min.css'
import {mapState} from 'vuex'

import HeaderTop from '../../components/HeaderTop/HeaderTop.vue'
import ShopList from '../../components/ShopList/ShopList.vue'

export default {
    data () {
      return {
        baseImageUrl: 'https://fuss10.elemecdn.com'
      }
    },
    mounted () {
      this.$store.dispatch('getCategorys')
      this.$store.dispatch('getShops')
     
    },
    computed: {
        ...mapState(['address', 'categorys', 'userInfo']),
        //根据categorys 一维数组生成一个二维数组，小数组中的元素最大是8
        categorysArr () {
          const {categorys} = this;
          //准备空的2维数组
          const arr = [];
          //准备一个小数组（最大长度为8）
          let minArr = [];
          //遍历categorys
          categorys.forEach(c => {
            //如果当前小数组已经满了，创建一个新的minArr
            if (minArr.length === 8) {
              minArr = []
            }
            //如果当前minArr是空的，将小数组保存到大数组中
            if (minArr.length === 0) {
              arr.push(minArr)
            }
            //将当前分类保存到minArr中
            minArr.push(c)
          });
          return arr
        }
    },
    watch: {
      categorys (value) { //categorys数组中有数据，在异步更新界面之前执行
      /**使用setTimeOut可以实现效果，不推荐 
        setTimeout( () => {
          //创建一个Swiper对象实现轮播
          new Swiper ('.swiper-container', {
            loop: true,  //可以循环轮播
            //如果需要分页器
            pagination: {
              el: '.swiper-pagination'
            }
          })
        }, 100)*/

        //界面更新就立即创建Swiper对象
        this.$nextTick( () => { //一旦完成界面更新，立即调用（此条语句写在数据更新之后）
          new Swiper ('.swiper-container', {
            loop: true,  
            pagination: {
              el: '.swiper-pagination'
            }
          })
        })
         
      }
    },
    components: {
      HeaderTop,
      ShopList
    }
}
</script>

<style lang="stylus" scoped>
@import "../../common/stylus/mixins.styl"
.msite  //首页
    width 100%
    .msite_nav
      bottom-border-1px(#e4e4e4)
      margin-top 45px
      height 200px
      background #fff
      .swiper-container
        width 100%
        height 100%
        .swiper-wrapper
          width 100%
          height 100%
          .swiper-slide
            display flex
            justify-content center
            align-items flex-start
            flex-wrap wrap
            .link_to_food
              width 25%
              .food_container
                display block
                width 100%
                text-align center
                padding-bottom 10px
                font-size 0
                img
                  display inline-block
                  width 50px
                  height 50px
              span
                display block
                width 100%
                text-align center
                font-size 13px
                color #666
        .swiper-pagination
          >span.swiper-pagination-bullet-active
            background #02a774
    .msite_shop_list
      top-border-1px(#e4e4e4)
      margin-top 10px
      background #fff
      .shop_header
        padding 10px 10px 0
        .shop_icon
          margin-left 5px
          color #999
        .shop_header_title
          color #999
          font-size 14px
          line-height 20px
      
</style>